Compliant solid-state bumper for robot

ABSTRACT

A robot bumper including a bumper body having a forward surface and a top surface angling away from the forward surface. The bumper body conforms to a shape of a received robot chassis. The robot bumper also includes a force absorbing layer disposed on the bumper body, a membrane switch layer comprising a plurality of electrical contacts arranged along the top surface of the bumper body, and a force transmission layer disposed between the force absorbing layer and the membrane switch layer. The force transmission layer includes a plurality of force transmitting elements configured to transmit force to the membrane switch layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This U.S. patent application is a divisional of, and claims priorityunder 35 U.S.C. §121 from, U.S. patent application Ser. No. 13/803,617,filed on Mar. 14, 2013, which claims priority under 35 U.S.C. §119(e) toU.S. Provisional Application 61/611,550, filed on Mar. 15, 2012. Thedisclosures of these prior applications are considered part of thedisclosure of this application and are hereby incorporated by referencein their entireties.

TECHNICAL FIELD

This disclosure relates to a tool for a robot to interact with itsphysical environment, allowing the robot to detect an impact with anobject and to determine the degree or force of the impact, the locationof the impact, and/or the direction of the impact. The presentdisclosure also provides a bumper to protect a robot from such impacts.

BACKGROUND

Historically, robot touch sensors are incorporated into a robot bumperassembly. Such bumper assemblies are rigid, movable bumpers that arespaced away and suspended from the robot chassis. Typically, suchbumpers include a rigid outer shell suspended from the robot chassis bya series of hardware, such as pivots/bumper arms and coil springs. Thesprings absorb the impact energy, but require a high impact force, i.e.,require that the bumper deflect by several millimeters to absorb theenergy before triggering a switch to indicate that an impact event hasoccurred. The deflection of the rigid bumper relative to the robot'srigid chassis not only requires a swept volume to actuate, but createsvisual seams and pinch points on the exterior. The use of the arms andsprings require a number of moving parts that create mechanical mountingcomplexities and can lead to mechanical failure. The distance betweenthe bumper and the robot creates a space in which dust and debris cancollect.

Detecting the location of the impact is limited by the number ofswitches and suspension points that economically can be incorporatedinto the robot's mechanical geometry. For many robots, two switches, aleft switch and a right switch, are used. At best, this allows for threedetection zones, right, left, and center if both switches are triggered.The geometrical limitations in using such switches prevent the abilityof the robot to detect when it is receiving pressure from above, such asin a wedging situation. Similarly, the robot cannot determine the degreeor force of impact.

An alternative bumper design that does not employ complex mechanicalmounting, utilizes carbon puck type contacts positioned around a frontportion of the robot. Such a structure has several drawbacks. Forexample, the weight of the carbon puck bumper structure is heavy andchanges the center of gravity of the robot. Additionally, the carbonpuck bumper structure is expensive to manufacture and the appearance ofthe bumper is not uniform, making it less than aesthetically pleasing toa consumer.

SUMMARY

One aspect of the disclosure provides a robot bumper assembly includinga bumper body, and first and second sensor arrays. The first sensorarray is disposed along and contoured to the periphery of a forwardfacing portion of the bumper body. The first sensor array senses contactwith an external environment at positions along the contour of theperiphery forward facing portion of the bumper body. The second sensorarray is disposed along and contoured to the periphery of a top portionof the forward facing portion of the robot body. The top portion isangled. ramping up. The second sensor array senses contact with anexternal environment at positions along the periphery of the angled topportion of the bumper body.

Implementations of the disclosure may include one or more of thefollowing features. The first sensor array may extend vertically alongthe height of the forward facing portion of the bumper body. In someexamples, the robot bumper further includes a third sensor arraydisposed along and contoured to the periphery of a forward facingportion of the bumper body. The third sensor array senses contact withan external environment at positions along the contour of the peripheryof the forward facing portion of the bumper body. The third sensor maybe spaced vertically apart from the first sensor array along the forwardfacing portion of the bumper body. The first and second sensor arraysmay be pressure sensitive. Additionally or alternatively, the secondsensor array may extend vertically along the height of the angled topportion of the bumper body. In some examples, the angled top portion iscurved.

In some implementations, the robot bumper further includes a fourthsensor array. The fourth sensor array may be disposed adjacent thesecond sensor array along the periphery of the angled top portion of theforward facing portion of the bumper body. In addition, the fourthsensor array may be contoured to the surface of the angled top portionand may sense contact with an external environment at positions alongthe periphery of the angled top portion of the bumper body. The bumperbody may define a substantially circular periphery or an at leastpartially square periphery.

In some examples, the robot bumper assembly may include a non-contactsensor array disposed on the forward facing portion of the bumper body.The non-contact sensor array may be vertically spaced between the firstsensor array and second sensor array. The first and second sensorsarrays may be membrane switches having first and second conductivelayers separated by a separator layer.

Another aspect of the disclosure provides a robot including a robotchassis having a side edge defining a periphery of the robot chassis anda top edge. The robot includes a membrane switch for sensing an impactbetween the robot chassis and an external environment and a forcetransmission layer for transmitting energy from an impact between therobot chassis and an external environment to the membrane switch.

In some implementations, the membrane switch senses an impact on theside edge and the top edge of the robot chassis. Additionally, themembrane switch may have a first sensitivity along the side edge of therobot chassis and a second sensitivity along the top edge of the robotchassis. The first sensitivity may be greater than the secondsensitivity. Additionally or alternatively, the membrane switch extendsaround an entirety periphery of the robot chassis. The robot chassis mayhave an approximately circular periphery or a partially squareperiphery. In some examples, the membrane switch includes first andsecond conductive layers separated by a separator layer.

Another aspect of the disclosure provides a robot bumper including aforce absorption layer, a membrane switch layer having a plurality ofelectrical contacts, and a force transmission layer comprising aplurality of force transmitting elements configured to transmit force tothe switch layer. In some examples, the membrane switch layer includes afirst sheet having a plurality of electrical contact points and a secondsheet having a plurality of electrical contact points. The switch layermay further comprise a separator layer positioned between the first andsecond sheets and for preventing accidental or incidental contactbetween the plurality of electrical contact points on the first andsecond sheets. Additionally or alternatively, the electrical contactpoints on the first sheet form a first pattern and the electricalcontact points on the second sheet form a second pattern. In someexamples, the first pattern and the second pattern are identical.

In some implementations, the plurality of electrical contact points oneach sheet form a plurality of zones, each zone corresponding to animpact point on an external surface of the bumper. Additionally, eachelectrical contact point may form an individual zone.

In some examples, the force transmission layer is positioned between theforce absorption layer and the membrane switch layer. The bumper mayconform to a shape of a robot chassis.

Objects and advantages of the present disclosure will be set forth inpart in the description which follows, and in part will be obvious fromthe description, or may be learned by practice of the present teachings.The objects and advantages of the present disclosure can be realized andattained by means of the elements and combinations particularly pointedout in the appended claim.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are not restrictive of the present teachings, as claimed.

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate exemplary embodiments of thepresent teachings and together with the description, serve to explainthe principles of those teachings.

DESCRIPTION OF DRAWINGS

FIG. 1A is a front top perspective view of an exemplary robot.

FIG. 1B is a rear bottom perspective view of the robot shown in FIG. 1A.

FIG. 1C is an exploded view of the robot shown in FIG. 1A.

FIG. 1D is a schematic view of an exemplary robot.

FIG. 2A is an exploded cross-sectional view of an exemplary bumperassembly.

FIG. 2B is an exploded cross-sectional view of another exemplary bumperassembly.

FIG. 3 illustrates an exploded perspective view of an exemplary bumperassembly on a robot.

FIG. 4A is a front view of an exemplary first conductive layer of amembrane switch assembly of a bumper.

FIG. 4B is a front view of an exemplary second conductive layer of amembrane switch assembly of a bumper.

FIG. 4C is a side view of an exemplary separator layer of a membraneswitch assembly of a bumper.

FIG. 4D is a perspective view of an exemplary separator layer of amembrane switch assembly separating first and second conductive layers.

FIG. 4E is a perspective view of an exemplary separator layer of amembrane switch assembly separating first and second conductive layers.

FIG. 5A is a perspective view of an exemplary conductive layer of amembrane switch assembly and a force transmitting layer of a bumperassembly.

FIGS. 5B and 5C are schematic views of exemplary conductive layers of amembrane switch assembly.

FIG. 6A is a perspective view of an exemplary membrane switch assemblyof a bumper.

FIG. 6B is a section view of an exemplary membrane switch assembly of abumper.

FIG. 7 is a perspective view of an exemplary force transmitting layer ofa bumper assembly.

FIGS. 8A-8D are schematic top views of exemplary robot chasses having abumper.

FIG. 9A is a schematic view of an exemplary conductive layer of amembrane switch assembly.

FIG. 9B is a perspective view of an exemplary membrane switch assemblylayer applied to a cylinder.

FIG. 9C is a perspective view of an exemplary manipulator having amembrane switch assembly layer applied to a cylindrical arm portion ofthe manipulator.

FIG. 9D is a schematic view of applying a membrane switch assembly indifferent robotic applications.

FIG. 10 is a schematic side view of an exemplary portion of a robot andsensor arrays thereon.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

Referring to FIGS. 1A-1D, in some implementations, a robot 100 includesa body 104 supported by a drive system 128 that can maneuver the robot100 across a floor surface 10 based on a drive command having x, y, andθ components, for example, issued by a controller 200. The robot body104 has a forward portion 112 and a rearward portion 114 carried by thebody 104. The drive system 128 includes right and left driven wheelmodules 128 a, 128 b. The wheel modules 128 a, 128 b are substantiallyopposed along a transverse axis X defined by the body 104 and includerespective drive motors 122 a, 122 b driving respective wheels 124 a,124 b. The drive motors 122 a, 122 b may releasably connect to the body104 (e.g., via fasteners or tool-less connections) with the drive motors122 a, 122 b optionally positioned substantially over the respectivewheels 124 a, 124 b. The wheel modules 128 a, 128 b can be releasablyattached to the chassis 104 and forced into engagement with the cleaningsurface 10 by respective springs. The robot 100 may include a casterwheel 126 disposed to support a forward portion 112 of the robot body104. The robot body 104 supports a power source 103 (e.g., a battery)for powering any electrical components of the robot 100.

The robot 100 can move across the surface 10 through variouscombinations of movements relative to three mutually perpendicular axesdefined by the body 104: a transverse axis X; a fore-aft axis Y; and acentral vertical axis Z. A forward drive direction along the fore-aftaxis Y is designated F (sometimes referred to hereinafter as “forward”),and an aft drive direction along the fore-aft axis Y is designated A(sometimes referred to hereinafter as “rearward”). The transverse axis Xextends between a right side R and a left side L of the robot 100substantially along an axis defined by center points of the wheelmodules 128 a, 128 b.

In some implementations, the robot 100 includes a cleaning system 300for cleaning or treating the floor surface 10. The cleaning system 300may include a dry cleaning system 300 a and/or a wet cleaning system 300b.

A user interface 102 may be disposed on a top portion of the body 104receives one or more user commands and/or displays a status of the robot100. The user interface 102 is in communication with the robotcontroller 200 such that one or more commands received by the userinterface 102 can initiate execution of a cleaning routine by the robot100.

The robot controller 200 (e.g., executing on a computing processor) mayexecute behaviors that cause the robot 100 to take an action, such asmaneuvering in a wall following manner, a floor scrubbing manner, orchanging its direction of travel when an obstacle is detected. The robotcontroller 200 can maneuver the robot 100 in any direction across thesurface 10 by independently controlling the rotational speed anddirection of each wheel module 128 a, 128 b. For example, the robotcontroller 200 can maneuver the robot 100 in the forward F, reverse(aft) A, right R, and left L directions. The robot controller 200 maydirect the robot 100 over a substantially random (e.g., pseudo-random)path while traversing the cleaning surface 10. The robot controller 200can be responsive to one or more sensors (e.g., bump, proximity, wall,stasis, and cliff sensors) disposed about the robot 100. The robotcontroller 200 can redirect the wheel modules 128 a, 128 b in responseto signals received from the sensors, causing the robot 100 to avoidobstacles and clutter while maneuvering the surface 10. If the robot 100becomes stuck or entangled during use, the robot controller 200 maydirect the wheel modules 128 a, 128 b through a series of escapebehaviors so that the robot 100 can escape and resume normal cleaningoperations.

In some implementations, to achieve reliable and robust autonomousmovement, the robot 100 includes a sensor system 500 supported by therobot body 104 and having one or more types of sensors 505, which can beused to create a perception of the robot's environment sufficient toallow the robot 100 to make intelligent decisions about actions to takein that environment. The sensor system 500 may include obstacledetection obstacle avoidance (ODOA) sensors, communication sensors,navigation sensors, etc. These sensors may include, but are not limitedto, proximity sensors, contact sensors, a camera (e.g., volumetric pointcloud imaging, three-dimensional (3D) imaging or depth map sensors,visible light camera and/or infrared camera), sonar, imaging sonar,radar, LIDAR (Light Detection And Ranging, which can entail opticalremote sensing that measures properties of scattered light to find rangeand/or other information of a distant target), LADAR (Laser Detectionand Ranging), ranging sonar sensors, a laser scanner, etc.

A forward portion 112 of the body 104 carries a bumper assembly 108,which detects (e.g., via one or more sensors) one or more events in adrive path of the robot 100, for example, as the wheel modules 128 a,128 b propel the robot 100 across the cleaning surface 10 during acleaning routine. The robot 100 may respond to events (e.g., obstacles,cliffs, walls) detected by the bumper assembly 108 by controlling thewheel modules 128 a, 128 b to maneuver the robot 100 in response to theevent (e.g., away from an obstacle). The bumper assembly 108 provides asensing capability and thus feedback when the robot comes into physicalcontact with the external environment. Additionally, the bumper assembly108 protects the elements of the robot 100 from impact forces caused bysuch physical contact. While some sensors are described herein as beingarranged on the bumper assembly 108, these sensors can be additionallyor alternatively arranged at any of various different positions on therobot 100.

Referring to FIG. 2A, the bumper assembly 108 may include several layersdisposed on each other. The layers include an innermost layer 110 (alsoreferred to as an internal frame layer), a sensing layer 120 (alsoreferred to as a membrane switch assembly layer), a force transmittinglayer 185 (also referred to as an activation layer), a force absorbinglayer 188 (also referred to as a shock absorbing layer), and an externallayer 190 (also referred to as an outer protective layer). The bumperassembly 108 may not include all of the above layers, or alternatively,some of the elements of the above layers may be incorporated into asingle layer. The sensing system 500 may include the membrane switchassembly layer 120, which may provide contact signals to the controller200.

As shown in FIG. 2A, the innermost layer 110 (also referred to as theforward facing portion of the robot body 107) may be an inner solid wall110 of the bumper assembly 108 formed by a chassis 104 of a robot 100 onwhich the bumper assembly 108 is coupled or mounted, or may be aseparate component of the bumper assembly 108. The wall 110 may be madeof a rigid plastic, e.g., an ABS (acrylonitrile butadiene styrene)material, and formed to provide a smooth surface against which thesensing layer 120 may be positioned. ABS is a type of polymer thatbecomes bendable when it reaches a specific temperature. When ABS coolsit goes back to its solid state. The smoothness of the surface reducesthe potential for erroneous actuation of the sensing layer 120. Only theportions of the innermost layer 110 that will come into contact with thesensing layer 120 provide a smooth surface for positioning adjacent thesensing layer 120. For example, if the robot chassis 104 includeswindows or openings 106 in an area that receives the bumper assembly108, both the innermost layer 110 and any additional layers of thebumper assembly 108, such as the sensing layer 120, can include openings106 that correspond to the chassis openings 104, as shown in FIG. 3.

Referring again to FIG. 1, in some implementations, the sensing ormembrane switch assembly layer 120 includes three layers, a firstconductive layer 130, a second conductive layer 140, and an interveningseparation layer 150 positioned between the first and second conductivelayers 130, 140. Each of the first and second conductive layers, 130,140 as well as the separation layer 150 may be made of a flexiblematerial such as polyethylene terephthalate (PET) or indium tin oxide(ITO).

Referring to FIGS. 4A-4E, each conductive layer 130, 140 may form aflexible substrate that includes a plurality of electrical contacts 160a, 160 b, respectively. As shown in FIGS. 5A-5C and 7, the electricalcontacts 160 a, 160 b may form part of a circuit 165 provided on eachflexible conductive layer 130, 140. The circuit 165 including electricalcontacts 160 a, 160 b on each conductive layer 130, 140 may be a circuitprinted on the flexible substrate 130, 140. Each conductive layer 130,140 may include, for example, a polyester film screen-printed with aconductive ink such as copper, silver, or graphite. Other types ofmaterials suitable for printed circuits, as known in the art, may beused to form first and second conductive layers 130, 140.

In some implementations, the separation layer 150 is a layer ofdielectric ink. The dielectric ink layer 150 may be printed directly onone of the conductive layers 130, 140 to act as an insulator between thetwo conductive layer 130, 140. This creates a controllable clearance gapC between the first and second conductive layers 130, 140 based on thethickness and number of layers of the dielectric ink that are printed.Having a dielectric ink as the separation layer 150 eliminates the needto use an insulating film to create the gap. The location, spacing,shape, and thickness of the dielectric ink layer may be adjusted to tunethe activation force of the switch in various regions of the bumperassembly 108.

As shown in FIGS. 4D and 6A, the electrical contacts 160 a, 160 b formedon the first and second conductive layers 130, 140 may face one another,separated by separation layer 150. When an electrical contact 160 a onfirst conductive layer 130 is brought into contact with an electricalcontact 160 b on second conductive layer 140, the switch is “ON” andwhen contact is broken, the switch is “OFF.” The membrane switchassembly 120 may be connected and transmit signals to the controller 200(e.g., a computing processor) to indicate when and where an impact isdetected. The controller 200 may be configured to detect and recognizesize, location, and number of impacts. The impacts may be identified byzone, for example, front, rear, side, top, etc. or by a matrix.

Referring again to FIGS. 2A and 4C, in some implementations, theelectrical contacts 160 a on the first conductive layer 130 areseparated from the electrical contacts 160 b on the second conductivelayer 140 by the separation layer 150. The separation layer 150 maydefine a plurality of openings 170 through which the electrical contacts160 a on the first conductive layer 130 may be brought into contact withthe electrical contacts 160 b on the second conductive layer 140.

The sensitivity of the sensing or membrane switch assembly layer 120 maybe controlled, in part, by the density of the electrical contacts 160 a,160 b provided on the first and second conductive layers 130, 140. Asshown in FIGS. 4A and 4B, each conductive layer 130, 140 may include thesame number of electrical contacts 160 a, 160 b or a differing number ofelectrical contacts 160 a, 160 b. The electrical contacts 160 a, 160 bmay be identically patterned on first and second conductive layers 130,140 or may have different patterns, sizes, and shapes. The greater thenumber of opportunities for the electrical contacts 160 a on the firstconductive layer 130 to come into contact with the electrical contacts160 b on the second conductive layer 140, the more sensitive themembrane switch assembly 120. Similarly, the size, shape, and positionof the openings 170 in separation layer 150 controls the number ofplaces (or opportunities) that contact may occur between the electricalcontacts 160 a on conductive layer 130 to come into contact with theelectrical contacts 160 b on the second conductive layer 140. Eachopening 170 in separation layer 150 provides an opportunity for contactbetween the electrical contacts 160 a on the first conductive layer 130and the electrical contacts 160 b on the second conductive layer 140.

In some implementations, the first and second conductive layers 130,140, (e.g., printed circuit boards (PCB)), are heat stabilized polyesterfilms screen printed with a silver printed circuit. The first and secondconductive PCB layers 130, 140 are 0.127 mm thick. The separation layer150 (with opening 170 in it) is a membrane switch spacer having athickness of 0.0254 mm. Each of the three layers (first and secondconductive layers 130, 140, and separator layer 150) defines alignmentholes to align them relative to one another. The innermost conductivelayer 130 may be glued to the innermost layer 110 (e.g., a plastic wall)and the three layers 130, 140, 150 of the sensing layer 120 can beattached using double-sided tape. It is also possible to manufacture thetwo conductive layers (PCBs) 130, 140 and the separator layer 150 as asealed unit.

Compressing the first and second conductive layers 130, 140 togetherresults in an electrical connection when electrical contacts 160 a, 160b come into contact with one another. The extent or number of contactsmade when the first and second conductive layers 130, 140 are compressedtogether may be representative of the size or force of the impact on thebumper assembly by the external environment. The amount of contact maybe determined by the contact points 160 a, 160 b or by zones 132 a-n,142 a-n. For example, as shown in FIGS. 5A and 5B, the first and secondconductive layers 130, 140 each include electrical contacts 160 a, 160 bidentically positioned and divided into six different zones 132 a-f, 142a-f. Alternatively, if the electrical contacts 160 a, 160 b areconnected vertically (e.g., six zones 132 a-f) on one conductive layer130 and horizontally (e.g., six zones 142 a-f) on the other conductivelayer 140, a simple x-y map of potential zones (e.g., 36 zones) where acontact is taking place is possible without any increase in the numberof electrical contacts 160 a, 160 b. This allows a finer localization ofimpact points. The concept also may be implemented such that multiplezones 132 a-f, 142 a-f are read simultaneously, allowing the bumperassembly 108 to act as a multi-touch sensor, and as a measure of theforce of the impact by the number of zones 132 a-f, 142 a-fsimultaneously triggered. In some examples, the zones 132 a-f, 142 a-fof the conductor layers 130, 140 each has a height of 1.8 inches.Additionally, the first zone 132 a, 142 a and the sixth zone 132 f, 142f may each have a width of 3.5 inches. The second zone 132 b, 142 b andthe fifth zone 132 e, 142 e may each have a width of 4.2 inches.Finally, the third zone 132 c, 142 c and the forth zone 132 d, 142 d mayeach have a width of 3.05 inches.

In some implementations, referring to FIG. 4D, the separation layer 150is made of piezoresistive material. When pressure is applied topiezoresistive material, the piezoresistive material experiences achange in resistance. Such a change in resistance causes changes ininter-atomic spacing making it easier for the conductive band to conductelectrons. The movement of electrons results in a change in theresistivity of the piezoresistive material. Piezoresistivity is measuresbased on the following equation:

$\begin{matrix}{\rho_{\sigma} = \frac{\left( \frac{\delta\;\rho}{\rho} \right)}{ɛ}} & (1)\end{matrix}$

where ρ_(σ) is the piezorisistivity, δρ is the change in resistivity, ρis the original resistivity, and ∈ is the strain. The two conductivelayers 130, 140 sandwich the piezoresistive material that forms theseparation layer 150. In some examples, an outer shock or forceabsorbing layer 188 made of rubber or neoprene is used to distributeforce and limit concentrated impact. Piezoresistive materials that maybe used include, but are not limited to, Velostat by 3M and Linqstat byCaplinq. The piezoresistive material as the separation layer 150 aids indetermining the pressure applied to a specific zone of the bumperassembly 108; requiring less mechanical travel, is calibrate-able, andmay be less susceptible to mechanical fatigue.

Adjacent and exterior to the membrane switch assembly layer 120 is aforce transmitting or activation layer 180. The force transmitting layer180 may be made of a urethane foam material designed to resist permanentcompression set. An example of a suitable material is Poron® urethanefoam. The force transmitting layer 180 may have a thickness that rangesbetween about 5/16″ and about 3/16″, and may have a thickness ofapproximately 0.5 mm. As shown in FIGS. 2A, 3, 5 and 7, the forcetransmitting layer 180 includes a plurality of force transmittingelements 185. The force transmitting elements 185 are small protrusionsextending from a surface 182 of the force transmitting layer 180 and arepositioned adjacent to the membrane switch assembly layer 120. The sizeand shape of the force transmitting elements 185 may vary as necessaryto transmit a force applied to the bumper assembly 108 to the membraneswitch assembly layer 120 through the force transmitting layer 180 viaforce transmitting elements 185. Additionally, the stiffness of the foammaking up the force transmitting layer 180 and elements 185 may beincreased or decreased to further vary the sensitivity of the membraneswitch assembly layer 120. Such variations in the stiffness of the foamand the dimensions of the force transmitting elements 185 can be used tocalibrate the amount of force necessary to actuate the membrane switchassembly layer 120. For example, the membrane switch assembly layer 120may be actuated by a force between about 0.5 lbs and about 0.151 bs. Asmall force such as 0.25 lbs is sufficient to indicate an impact withthe external environment but will not stop the robot 100 for incidentalcontact, such as with, for example, a bed skirt, but the forcesensitivity can be tuned higher or lower based on capabilities of themembrane switch layer 120.

The number of force transmitting elements 185 may be the same as thenumber of potential electrical contact points 160 a, 160 b between thefirst and second conductive layers 130, 140. The force transmittingelements are sizable and positionable to be aligned with each electricalcontact 160 a, 160 b on the first and second conductive layers 130, 140of membrane switch assembly layer 120. For example, the forcetransmitting elements 185 may be round and have a diameter equal to adiameter of electrical contracts 160 a, 160 b. For example, the forcetransmitting elements 185 may have a diameter of 8 mm and a height of1.25 mm. Thus, the force transmitting elements 185 serve to channel aportion of impact energy to the contact points of the membrane switchassembly layer 120. When such energy is transmitted to the membraneswitch assembly layer 120 and is sufficient to place at least oneelectrical contact 160 a of first conductive layer 130 into contact withat least one electrical contact 160 b of second conductive layer 140,the membrane switch is “ON” for the duration of the contact.

Similar to the force transmitting layer 180, the shock or forceabsorbing layer 188 may be fabricated from a urethane foam materialdesigned to resist permanent compression set. An example of a suitablematerial is Paron® urethane foam. Additional exemplary materials includeEVA foam (Core material), a polyurethane elastomeric. Shock absorbinglayer 188 may have a thickness suitable to absorb a significant portionof the force from an impact of the bumper 108 with the externalenvironment in order to protect the chassis 104 of the robot 100. Inparticular, the bumper 108 should absorb the full impact of thecollision to protect the robot 100 from impact forces as the robot 100moves at a top speed of 1 ft/sec, and it should reduce and/or eliminatethe noise from such impact. In some examples, the shock or forceabsorbing layer 188 may be integrated with the force transmitting layer180.

In some implementations, the exterior of the bumper assembly 108 isprovided with an outer protective layer or coating 190. The outerprotective layer 190 may form an abrasion-resistant skin that serves toprotect the bumper assembly 108 from wear, cuts, and punctures. Anysuitable elastomeric material, for example a reinforced vinyl material,may be used. The outer protective layer 190 may have a thickness of, forexample, about 1 mm. The outer protective layer 190 may be formedintegrally with the shock or force absorbing layer 188. In suchimplementation, the shock or force absorbing layer 188 may be made of apolyurethane foam and covered with a polyurethane skin. An example of anappropriate material is a polyurethane manufactured and used by Vibram®.

Referring to FIGS. 2A and 6B, in some implementations, the firstconductive layer 130 of the sensing layer 120 includes rows of contacts160 that sit on a smooth surface 110 (i.e., the forward facing portionof the robot body 107). The first conductive layer 130 lies on aseparation layer 150. The separation layer 150 includes openings 170. Aspreviously discussed, the openings 170 may be adjusted in diameter toadjust the sensitivity of the membrane switch assembly layer 120 andtherefore adjusting the sensitivity of the bumper assembly 108. Thesecond conductive layer 140 may include a switch matrix that closes theswitch if in contact with the first conductive layer 130. Adjacent tothe second conductive layer 140 is a force transmitting or activationlayer 180. The force transmitting or activation layer 180 may includetwo layers that are attached to the first conductive layer 130 by kisscutting and dies. The first layer includes force transmitting elements185. The second layer includes a surface 182. In some examples, theheight of the transmitting elements 185 is manipulated to adjust thesensitivity of the bumper assembly 108. The transmitting elements 185may be kiss cut. Kiss cutting is a process where the element backing isnot cut and the only cut is around the element, creating a protrusion(e.g., the transmitting elements 185). The surface 182 may be die cut.Die cutting cuts the shape of the element. Both die cutting and kisscutting use a die to cut the shape of the elements. The die is usuallycustomized to the specific requirements of the element. The surface 182is boned to the second conductive layer 140 and around the transmittingelements 185. The surface 182 provides a spacer between the transmittingelements 185 and the electrical contacts 160. The surface 182 and thetransmitting elements 185 may be made of a stiffer material than thefoam used in the shock absorbing layer 188 that deforms when the bumperassembly 108 is impacted. The shock absorbing layer 188 provides theshape of the bumper 108 and compresses when the bumper is impacted. Thecompression is transmitted through the foam of the shock absorbing layer188, and moves the transmitting elements 185, which then closes theswitch in the first conductive layer 130. In some examples, an externallayer 190 is used as an outer protective layer and provides a skin thatmay be adjusted in feel without consideration of the feel of the foamused in the shock absorbing layer 188. The external layer 190 increasesthe life of the bumper assembly 190 due to the protection it provides tothe member switch assembly 120.

As shown in FIGS. 3 and 8A-8D, the bumper assembly 108 may be used toform a bumper 108 b, 108 c that covers only a portion of the robotchassis 104 b, 104 c or a bumper 108 a, 108 d that surrounds the robotchassis 104 a, 104 d. The bumper assembly 108 is sufficiently flexibleto conform to a round contour (FIGS. 8A, 8B) of the robot chassis 104 a,104 b or may take on a square form (FIGS. 8C, 8D) to conform to a robotchassis 104 c, 104 d. Similarly, the flexibility of the bumper assembly108 permits the membrane switch assembly 120 to extend beyond a side ofthe chassis 104 and onto a top edge 109 (FIG. 1A) of the robot chassis104. Providing a membrane switch assembly layer 120 along a top edge ofthe robot chassis 104, permits detection of forces pushing down onto, orwedging, the chassis of the robot. This is particularly useful when therobot 100 is in an environment in which it may travel under low-hangingobjects. It may be desirable for a membrane switch assembly layer 120positioned on a top of a robot chassis 104 to be less sensitive than amembrane switch assembly layer 120 positioned on an edge of the robotchassis 104. As discussed above, the sensitivity of portions of themembrane switch assembly layer 120 may be varied by adjusting the size,spacing, and position of the electrical contacts 160 a, 160 b, the size,shape, and spacing of the openings 170 in the separator layer 150, andthe stiffness of the foam of force transmitting layer 180 as well as thesize and shape of the force transmitting elements 185.

The bumper assembly 108 may use approximately one third of the physicalvolume required by previous bumpers. It has no moving parts, thuseliminating mechanical mounting complexity, visual seams, and pinchpoints. The bumper assembly 108, as described, offers a virtuallyunlimited number of detection zones for vastly superior localization ofimpact points, and will allow an approximation of the force of an impactby counting the number of contact points detected. Finally, the bumperassembly 108 is useful as a full-surround bumper that can detect impactsfrom the front, sides, and rear, and also can detect wedging forces fromabove.

Referring to FIGS. 9A-9C, in some implementations the sensing ormembrane switch assembly layer 120 may be applied to a cylinder 400. Thecylinder 400 may be implemented in a robot for detecting any bump orpressure applied to the portion of the robot having the membrane switchassembly layer 120. In some examples, a robot 100 may include a robotarm 600 for manipulating and moving objects. The robot arm 600 mayinclude the cylinder 400 surrounded by the membrane switch assemblylayer 120. As described earlier, the sensing or membrane switch assemblylayer 120 may include a first conductive layer 130, a second conductivelayer 140, and an intervening separation layer 150. The first conductivelayer 130 extends horizontally and includes a conductive zone 132 a-f(e.g., strip of conductive tape) the second conductive layer 140 extendsvertically forming a grid pattern with the first conductive layer 130.In some examples, the first and second layers 130, 140 are perpendicularto one another. Additionally, a separation layer 150 extends the lengthof the horizontal first conductive layer 130. The separation layer 150may be a single sheet positioned between the first and second conductivelayers 130, 140.

In some implementations, the first conductive layer 130 is incommunication with the robot controller 200, which may include ananalog-to-digital converter (ADC) 210. An ADC 210 is a device forconverting a continuous physical quantity to a digital number. Thecontinuous physical quantity may be an electrical voltage and thedigital number represents the physical quantity's amplitude. The robotcontroller 200 may activate a single zone 132 a-f of the firstconductive layer 130 (e.g., allow/accept signals generated in that zone132 a-f) without activating the other zones 132 a-f of that layer 130.Additionally, the vertical second conductive layer 140 may also beconnected to the robot controller 200. When the robot controller 200activates a horizontal zone 132 a-f of the first conductive layer 130,the ADC 210 reads data for each of the vertical zones 142 a-fintersecting the activated horizontal zone 132 a-f. The collected ADCdata is indicative of the pressure being applied at a specific point onthe zone matrix formed by the first and second conductive layers 130,140.

Referring to FIG. 9D, in some implementations, the sensing or membraneswitch assembly layer 120 may have several applications such as roboticforearms 600 or as a skin 620 for a surrogate hand or finger. In someexamples, the sensing or membrane switch assembly layer 120 may bedispose on a base 602 for sensing a load distribution about the base602.

Referring to FIG. 10, in some implementations, the robot 100 includes abumper assembly 108 having a bumper body 107 carrying one or morediscretely placed obstacle sensors 120 a, 120 c and one or morediscretely placed wedge sensors 120 b, 120 d. The sensors 120 a-d can beany switch for indicating contact, such as, but not limited to, any ofthe implementations of the membrane switch assembly layer 120 describedabove, a capacitor/dielectric switch having a compressible dielectriclayer positioned between two capacitor layers, or any binary switch. Inthe example shown in FIG. 10, the sensors 120 a, 102 b are arrays of thesame type in the bump and wedge positions, the bump position beinglocated on a wall portion 110 of the bumper assembly 108 positioned inthe forward direction of travel F and the wedge position being locatedon a top surface 109, or “top ramp portion 109”, of the bumper body 107,which may be angled as indicated. Here, the descriptor “angled” includescurved surface contours. In some examples, the obstacle sensor arrays120 a, 120 b and optional wedge sensor arrays 120 c, 120 d may bepre-formed to match the contours of the wall portion 110 and top rampportion 109 of the bumper body 107. Moreover, the pre-formed sensorarrays 120 a-d may be of the piezoresistive membrane switch assemblytype described herein.

A first array of sensors 120 a may be disposed along the contour of thewall portion 110 of the bumper body 107 or the bumper assembly 108facing forward in the direction of travel F. The term “array” initiallymeans different sensing positions along the contour. Optionally, thearray 120 a also extends vertically for different sensing positionsalong the height of the wall portion 110 of the bumper body 107. Thismay be achieved by providing a continuous sensor array 120 a or two ormore discrete sensor arrays 120 a, 120 b positioned at discrete heightsalong the contour of the bumper 108 (i.e. along the peripheral bumperprofile). In this later implementation, the two discrete sensor arrays120 a, 120 c are separated by a non-contact ODOA sensor array 505.Separating the discrete bump sensor arrays 120 a, 120 c leaves anunoccupied portion of the wall portion 110 of the bumper body 107 forpositioning one or more additional sensors thereon and/or thereinwithout obstructing the field of view therefrom. In implementationshaving two or more bump sensor arrays 120 a, 120 c discretely positionedalong the height of the wall portion 110, the placement of these sensors120 a, 120 c at discrete positions along the height of the wall portion110 enables the robot 100 to sense contact in a range of locations alongthe robot 100 that bump into typically encountered objects (e.g. walls,chair legs, toe kicks, etc.).

In some implementations, a second array of sensors 120 b is disposedalong the top ramp portion 109 of the forward contour of the bumper body107, the portion of the bumper body 107 that angles back in a directionaway from the forward direction of travel F. The term “array” initiallymeans different sensing positions along the contour (i.e. along theperipheral bumper profile). Optionally, the array 120 b also extendsvertically for different sensing positions along the height of the rampportion 109 the bumper body 107. This may be achieved by providing acontinuous sensor array 120 b or two or more discrete sensor arrays 120b, 120 d positioned at discrete heights along the contour of the bumperbody 107 (i.e. along the periphery of the bumper assembly 108).

The two or more discrete bump sensor arrays 120 a, 120 c and two or morediscrete wedge sensor arrays 120 b, 120 d enable the robot 100 todiscern height of impact. The robot 100 may use the bump and wedgesensor arrays 120 a, 120 b and optional bump and wedge sensor arrays 120c, 120 d to compare timing of signals output from different arraypositions along the wall portion 110 and top ramp portion 109 todetermine whether obstacle contacted by the robot 100 is moving (e.g.bumping a moving shoe vs. a stationary chair leg).

As described above, the obstacle sensor arrays 120 a, 120 c and optionalwedge sensor arrays 120 b, 120 d may be adjusted to a sensing thresholdfor detecting a range of obstacles such as, but not limited to, softobstacles, moving obstacles, walls, and furniture vs. walls. The robot100 may use the obstacle sensor arrays 120 a, 120 c and optional wedgesensor arrays 120 b, 120 d to compare continuously or discretelyvariable pressure to determine the character of impacted material (e.g.,curtains).

In some examples, the robot 100 uses the wedge sensor arrays 120 b, 120d along the top ramp portion 109 of the forward contour of the bumperbody 107 to compare continuously or discretely variable pressure todetermine character of overhanging surface. For example, the robot 100can detect an increasing wedge risk because the vertical position of thesensor arrays 120 b, 120 d detecting contact is extending down the top109 of the robot, or a decreasing wedge risk because the verticalposition of the sensor arrays 120 b, 120 d detecting contact isextending up. Additionally or alternatively, the robot 100 may detect ahigh wedge risk because the surface area of wedging overhang contactingthe wedge sensor arrays 120 b, 120 d is wide and/or soft or the robot100 may detect a low wedge risk because surface area of wedging overhangcontacting the wedge sensor arrays 120 b, 120 d is narrow and/or hard.

Various implementations of the systems and techniques described here canbe realized in digital electronic and/or optical circuitry, integratedcircuitry, specially designed ASICs (application specific integratedcircuits), computer hardware, firmware, software, and/or combinationsthereof. These various implementations can include implementation in oneor more computer programs that are executable and/or interpretable on aprogrammable system including at least one programmable processor, whichmay be special or general purpose, coupled to receive data andinstructions from, and to transmit data and instructions to, a storagesystem, at least one input device, and at least one output device.

To provide for interaction with a user, one or more aspects of thedisclosure can be implemented on a computer having a display device,e.g., a CRT (cathode ray tube), LCD (liquid crystal display) monitor, ortouch screen for displaying information to the user and optionally akeyboard and a pointing device, e.g., a mouse or a trackball, by whichthe user can provide input to the computer. Other kinds of devices canbe used to provide interaction with a user as well; for example,feedback provided to the user can be any form of sensory feedback, e.g.,visual feedback, auditory feedback, or tactile feedback; and input fromthe user can be received in any form, including acoustic, speech, ortactile input. In addition, a computer can interact with a user bysending documents to and receiving documents from a device that is usedby the user; for example, by sending web pages to a web browser on auser's client device in response to requests received from the webbrowser.

While this specification contains many specifics, these should not beconstrued as limitations on the scope of the disclosure or of what maybe claimed, but rather as descriptions of features specific toparticular implementations of the disclosure. Certain features that aredescribed in this specification in the context of separateimplementations can also be implemented in combination in a singleimplementation. Conversely, various features that are described in thecontext of a single implementation can also be implemented in multipleimplementations separately or in any suitable sub-combination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asub-combination or variation of a sub-combination.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of the disclosure. Accordingly, otherimplementations are within the scope of the following claims. Forexample, the actions recited in the claims can be performed in adifferent order and still achieve desirable results.

What is claimed is:
 1. A robot bumper comprising: a bumper body having a forward surface and a top surface angling away from the forward surface, the bumper body conforming to a shape of a received robot chassis; a force absorbing layer disposed on the bumper body; a membrane switch layer comprising a plurality of electrical contacts arranged along the top surface of the bumper body; and a force transmission layer disposed between the force absorbing layer and the membrane switch layer, the force transmission layer comprising a plurality of force transmitting elements configured to transmit force to the membrane switch layer.
 2. The robot bumper of claim 1, wherein the membrane switch layer comprises a first sheet having a plurality of electrical contact points and a second sheet having a plurality of electrical contact points.
 3. The robot bumper of claim 2, wherein the membrane switch layer further comprises a separator layer positioned between the first and second sheets and configured to prevent accidental or incidental contact between the plurality of electrical contact points on the first and second sheets.
 4. The robot bumper of claim 3, wherein the separation layer comprises a piezoresistive material.
 5. The robot bumper of claim 2, wherein the electrical contact points on the first sheet form a first pattern and the electrical contact points on the second sheet form a second pattern.
 6. The robot bumper of claim 5, wherein the first pattern and the second pattern are identical.
 7. The robot bumper of claim 2, wherein the plurality of electrical contact points on each sheet form a plurality of zones, each zone corresponding to an impact point on an external surface of the bumper.
 8. The robot bumper of claim 7, wherein each electrical contact point forms an individual zone.
 9. The robot bumper of claim 1, wherein the layers conform to a shape of a robot chassis. 